<!DOCTYPE>
<html>
<head>
<style>
    #canvas {
        width: 200px;
        height: 200px;
        background-color: red;
    }
    .blue {
        width: 50px;
        height: 50px;
        background-color: rgba(0, 0, 255, 0.5);
        top: -50px;
        position: relative;
    }
</style>
</head>
<body>
<div id="canvas"></div>
<div class="blue"></div>
</body>
</html>
